<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
</head>
<body>
<script>
	let a = function () {
		this.a = 'a'
    };
    Object.defineProperty(a.prototype,'b', {
        value:'test',
	    enumberable:false
    });
//    a.prototype.b.enumerable = false;
    let c = new a();
	for(key in c){
        console.log(key);
	}
</script>
</body>
</html>